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Project phase 2014-2017 investigated the influence of land-use intensity on microbial abundance and function in grassland soils across a range of scales. In the first and second phase of the Biodiversity Exploratories project we found that land-use intensification alters the spatial distribution in soil microbial communities at the plot scale (10 m x 10 m). We demonstrated that most of the spatial variance can be explained only at small scales (<12 cm) or large scales (>10 m). Consequently, we focused our interest in the phase 2014-2017 towards these small- and large-scales.


We identified mechanisms that shape small-scale spatial patterns and link them to variations in land-use intensity. We investigated the following mechanisms that contribute to the development of spatial heterogeneity in soil microbial communities: (1) colonization of new surfaces (minerals, organo-mineral complexes and litter) and (2) resource partitioning between bacteria and fungi in the detritusphere and rhizosphere. These experiments provided novel insights into the physical and chemical niches occupied by soil microorganisms over time under different land-use intensities.


Reactive soil minerals, partially coated with dissolved organic matter (13C labelled artificial model exudates), were placed in mesh bags and buried in soils of selected grassland sites with contrasting land-use intensities (LUI) to assess the colonization and sorption of specific groups of microorganisms to mineral surfaces. In addition, we buried mesh bags filled with reactive soil minerals mixed with 13C and 15N labelled roots of Dactylis glomerata in the same grassland soils to assess how rapidly soil microorganisms and plants use this resource in soils of different LUIs. The exposure for the two different experiments were 6 months for the artificial root exudates and 31 months for the labelled roots. We used physiological, microbiological and isotopic methods to elucidate in situ colonization patterns, carbon use and levels of extracellular enzyme expression by soil microorganisms associated with mineral surfaces.

Photo shows mineral container being removed from grassland soil
Mineral containers being removed from the grassland soil.
Photo shows mineral container after exposure
Mineral container after exposure.

Microorganisms slowly colonized pristine mineral surfaces and established functionally distinct communities over time (Kandeler et al. 2019, Vieira et al. 2020). Fungi colonized mineral surfaces to a greater extent than bacteria, reaching 13.2% of control soils compared to 3.2% by bacteria after 31 months. Fungi also reached pristine mineral surfaces earlier than bacteria, probably due to their hyphal growth strategies, and made immediate use of the added complex root litter substrate. This result is evident by the incorporation of up to 74% root litter-derived C into the fungus-specific PLFA (18:2ω6,9) compared to 51% root litter-derived C in the bacteria-specific PLFAs. Both bacteria and fungi associated with minerals remained in an active state (high biomass-specific respiration, high bacterial and fungal growth rates) throughout the experimental period. Grassland LUI and physico-chemical properties of the adjacent soil modified both quantity and quality of substrates available to soil microorganisms in the mineralosphere. Since 13C-incorporation into microbial biomass was greater under low LUI than under high LUI, we conclude that microorganisms in low LUI sites had to rely on the added root material, while the carbon signal in microorganisms in the high LUI sites was diluted by alternative sources resulting from transport of dissolved organic carbon into the mineralosphere.

FTIR spectra indicated that mineral-associated artificial root exudates (ARE) were used within the first 2 weeks of exposure and were replaced by other carbohydrates derived from living or dead cells as well as soil-borne C sources transported into the mineralosphere after heavy rain events (Boeddinghaus et al. 2021). Fungi and Gram-positive bacteria incorporated ARE-derived C more rapidly than Gram-negative bacteria. Gram-negative bacteria presumably profited indirectly from the ARE by cross-feeding on mineral-associated necromass of fungi and Gram-positive bacteria. The Gram-negative bacterial phyla Verrucomicrobia, Planctomycetes, Gemmatimonadetes, Armatimonadetes, and Chloroflexi showed a positive correlation with Gram-negative PLFA abundances. After 24 weeks of exposure in the grassland soils, abundances of soil microorganisms in the mineralosphere reached only 3.1% of the population density in soil. In conclusion, both bacteria and fungi slowly colonize new surfaces such as pristine minerals, but quickly assimilate artificial root exudates, creating an active microbial community in the mineralosphere.


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Einfluss der Landnutzungsintensität auf die mikrobielle Bio-masse von Grünlandböden
Bauer C. (2018): Einfluss der Landnutzungsintensität auf die mikrobielle Bio-masse von Grünlandböden. Bachelor thesis, University Hohenheim
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Die Landnutzungsintensität verändert die räumliche Verteilung und Funktion von Bodenmikroorganismen im Grünland
Berner D., Marhan S., Keil D., Schützenmeister A., Piepho H.-P., Poll C., Kandeler E. (2010): Land-Use Intensity Modifies Spatial Distribution and Function of Soil Microorganisms in Grasslands. Pedobiologia 54 (5-6), 341-351. doi:10.1016/j.pedobi.2011.08.001
More information:  doi.org
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Impact of soil disturbance on microorganisms in differently managed grassland soils linked to the ecosystem resilience
Binder I. (2016): Impact of soil disturbance on microorganisms in differently managed grassland soils linked to the ecosystem resilience. Master thesis, University Hohenheim
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Räumliche und zeitliche Variationen von Mikroorganismen in Grünlandböden - Einflüsse von Landnutzungsintensität, Pflanzen und Bodeneigenschaften
Boeddinghaus R. S. (2019): Spatial and temporal variations of microorganisms in grassland soils - influences of land-use intensity, plants and soil properties. Dissertation, University Hohenheim
More information:  opus.uni-hohenheim.de
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Veränderungen von funktionellen Pflanzeneigenschaften erklären parallele Veränderungen in der Struktur und Funktion mikrobieller Gemeinschaften in Grünlandböden
Boeddinghaus R. S., Marhan S., Berner D., Boch S., Fischer M., Hölzel N., Kattge J., Klaus V. H., Kleinebecker T., Oelmann Y., Prati D., Schäfer D., Schöning I., Schrumpf M., Sorkau E., Kandeler E., Manning P. (2019): Plant functional trait shifts explain concurrent changes in the structure and function of grassland soil microbial communities. Journal of Ecology 107 (5), 2197-2210. doi: 10.1111/1365-2745.13182
More information:  doi.org
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Boeddinghaus R. S., Marhan S., Gebala A., Haslwimmer H., Vieira S., Sikorski J., Overmann J., Soares M., Rousk J., Rennert T., Kandeler E. (2021): The Mineralosphere – Interactive zone for microbial colonization and carbon use in grassland soils. Biology and Fertility of Soils 57, 587–601. doi: 10.1007/s00374-021-01551-7
More information:  doi.org
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Gibt es allgemeine räumliche Verteilungsmuster von mikrobieller Biomasse und Enzymaktivitäten in Grünlandböden?
Boeddinghaus R. S., Nunan N., Berner D., Marhan S., Kandeler E. (2015): Do general spatial relationships for microbial biomass and soil enzyme activities exist in temperate grassland soils? Soil Biology & Biochemistry 88, 430-440. doi: 10.1016/j.soilbio.2015.05.026
More information:  doi.org
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Einfluss der Landnutzungsintensität auf die mikrobielle Biomasse und Enzymaktivitäten im Rhizosphärenboden verschiedener Grünlandpflanzenarten
Boob M. (2015): Einfluss der Landnutzungsintensität auf die mikrobielle Biomasse und Enzymaktivitäten im Rhizosphärenboden verschiedener Grünlandpflanzenarten. Master thesis, Universität Hohenheim
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Einfluss von Landnutzungsintensität auf Mikroorganismen in Grünlandböden der Schwäbischen Alb
Breuer B.S. (2008): Einfluss von Landnutzungsintensität auf Mikroorganismen in Grünlandböden der Schwäbischen Alb. Bachelor Thesis, University Hohenheim
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Fiore-Donno A. M., Richter-Heitmann T., Degrune F., Dumack K., Regan K. M., Mahran S., Boeddinghaus R. S., Rillig M. C., Friedrich M. W., Kandeler E., Bonkowski M. (2019): Functional Traits and Spatio-Temporal Structure of a Major Group of Soil Protists (Rhizaria: Cercozoa) in a Temperate Grassland. Frontiers in Microbiology 10:1654. doi: 10.3389/fmicb.2019.01654
More information:  doi.org
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Räumliche Heterogenität mikrobieller Enzymaktivitäten in Grünlandböden der Schwäbischen Alb
Glatzle S.(2008): Räumliche Heterogenität mikrobieller Enzymaktivitäten in Grünlandböden der Schwäbischen Alb. Bachelor thesis, University Hohenheim
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Goldmann K., Boeddinghaus R. S., Klemmer S., Regan K. M., Heintz-Buschart A., Fischer M., Prati D., Piepho H.-P., Berner D., Marhan S., Kandeler E., Buscot F., Wubet T. (2020): Unraveling spatio‐temporal variability of arbuscular mycorrhiza fungi in a temperate grassland plot. Environmental Microbiology 22 (3), 873-888. doi: 10.1111/1462-2920.14653
More information:  doi.org
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Die Mineralosphäre – Sukzession und Physiologie von Bakterien und Pilzen während der Besiedlung reiner Minerale in Grünlandböden mit unterschiedlicher Landnutzungsintensität
Kandeler E., Gebala A., Boeddinghaus R. S., Müller K., Rennert T., Soares M., Rousk J., Marhan S. (2019): The mineralosphere – Succession and physiology of bacteria and fungi colonising pristine minerals in grassland soils under different land-use intensities. Soil Biology and Biochemistry 136: 107534. doi: 10.1016/j.soilbio.2019.107534
More information:  doi.org
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Einfluss von Landnutzung auf Abundanz, Funktion und räumliche Verteilung von N-umsetzenden Mikroorganismen in Grünlandböden
Keil D. (2015): Influence of land use on abundance, function and spatial distribution of N-cycling microorganisms in grassland soils. Dissertation, University of Hohenheim
More information:  opus.uni-hohenheim.de
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Einfluss von Landnutzungsintensität auf die räumliche Verteilung Stickstoff umsetzender Mikroorganismen in Grünlandböden
Keil D., Meyer A., Berner D., Poll A., Schützenmeister A., Piepho H.-P., Vlasenko A., Philippot L., Schloter M., Kandeler E., Marhan S. (2011): Influence of land-use intensity on spatial distribution of N-cycling microorganisms in grassland soils . FEMS Microbiology Ecology 77 (1), 95-106. doi: 10.1111/j.1574-6941.2011.01091.x
More information:  doi.org
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Einfluss von Temperaturerhöhung und Dürre auf Lachgasemissionen und die Häufigkeit von denitrifizierenden Bakterien in Grünlandböden mit unterschiedlicher Landnutzungsintensität
Keil D., Niklaus P. A., von Riedmatten L. R., Boeddinghaus R. S., Dormann K. F., Scherer-Lorenzen M., Kandeler E., Marhan S. (2015): Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land use. FEMS Microbiology Ecology 91(7), pii: fiv066. doi: 10.1093/femsec/fiv066
More information:  doi.org
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Long-term effects of disturbance and seed addition on soil microbial biomass in grassland with high and low land-use intensity
Langzeit Effect von Störung und Ansaat auf die mikrobielle Biomasse in Grünlandböden mit hoher und niedriger Landnutzungsintensität
Lang K. (2018): Long-term effects of disturbance and seed addition on soil microbial biomass in grassland with high and low land-use intensity. Bachelor thesis, University Hohenheim
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Eine neue Methode (midDRIFTS basierte Spektroskopie) erlaubt die schnelle und kostengünstige Vorhersage von mikrobieller Biomasse und Aktivität in Grünlandböden
Rasche F., Marhan S., Berner D., Keil D., Kandeler E., Cadisch G. (2013): midDRIFTS-based partial least square regression analysis allows predicting microbial biomass, enzyme activities and 16S rRNA gene abundance in soils of temperate grasslands. Soil Biology and Biochemistry 57, 504–512. doi: 10.1016/j.soilbio.2012.09.030
More information:  doi.org
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Regan K. M. (2016): Linking Microbial Abundance and Function to Understand Nitrogen Cycling in Grassland Soils. Dissertation, University Hohenheim
More information:  opus.uni-hohenheim.de
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Zeigen Pflanzen oder abiotische Bodeneigenschaften saisonal bedingt mehr Einfluss auf die Verteilung von Mikroorganismen in Grünlandböden?
Regan K. M., Nunan N., Boeddinghaus R. S., Baumgarten V., Berner D., Boch S., Oelmann Y., Overmann J., Prati D., Schloter M., Schmitt B., Sorkau E., Steffens M., Kandeler E., Marhan S. (2014): Seasonal controls on grassland microbial biogeography: Are they governed by plants, abiotic properties or both? Soil Biology and Biochemistry 71, 21–30. doi: 10.1016/j.soilbio.2013.12.024
More information:  doi.org
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Regan K., Stempfhuber B., Schloter M., Rasche F., Prati D., Philippot L., Boeddinghaus R. S., Kandeler E., Marhan S. (2017): Spatial and temporal dynamics of nitrogen fixing, nitrifying and denitrifying microbes in an unfertilized grassland soil. Soil Biology and Biochemistry 109, 214–226. doi: 10.1016/j.soilbio.2016.11.011
More information:  doi.org
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Richter-Heitmann T., Hofner B., Krah F.-S., Sikorski J., Wüst P. K., Bunk B., Huang S., Regan K., Berner D., Boeddinghaus R. S., Marhan S., Prati D., Kandeler E., Overmann J., Friedrich M. W. (2020): Stochastic dispersal rather than deterministic selection explains the spatio-temporal distribution of soil bacteria in a temperate grassland. Frontiers in Microbiology 11: 1391. doi: 10.3389/fmicb.2020.01391
More information:  doi.org
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Die potentielle Methan-Oxidation des Bodens in Abhängigkeit von der Landnutzungsintensität am Beispiel von Grünland und Wald
Rohrbach K. (2017): Die potentielle Methan-Oxidation des Bodens in Abhängigkeit von der Landnutzungsintensität am Beispiel von Grünland und Wald. Bachelor thesis, University Hohenheim
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Erholung von Ökosystemfunktionen nach experimenteller Störung in 73 Grünlandflächen mit unterschiedlicher Landnutzungsintensität, Artenvielfalt und Zusammensetzung der Pflanzengesellschaft
Schäfer D., Klaus V. H., Kleinebecker T., Boeddinghaus R. S., Hinderling J., Kandeler E., Marhan S., Nowak S., Sonnemann I., Wurst S., Fischer M., Hölzel N., Hamer U., Prati D. (2019): Recovery of ecosystem functions after experimental disturbance in 73 grasslands differing in land‐use intensity, plant species richness and community composition. Journal of Ecology 107 (6), 2635-2649. doi: 10.1111/1365-2745.13211
More information:  doi.org
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Lineare gemischte Modelle und Geostatistik für geplante Experimente in den Bodenwissenschaften – zwei unversöhnliche Methoden oder zwei Seiten derselben Medaille
Slaets J., Boeddinghaus R. S., Piepho H.-P. (2021): Linear mixed models and geostatistics for designed experiments in soil science ‐ two entirely different methods or two sides of the same coin? European Journal of Soil Science 72 (1), 47-68. doi: 10.1111/ejss.12976
More information:  doi.org
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Nach welchen Regeln besiedeln Bakterien den Boden?
Vieira S., Sikorski J., Gebala A., Boeddinghaus R. S., Marhan S., Rennert T., Kandeler E., Overmann J. (2020): Bacterial colonization of minerals in grassland soils is selective and highly dynamic. Environmental Microbiology 22 (3), 917-933. doi: 10.1111/1462-2920.14751
More information:  doi.org

Scientific assistants

Prof. Dr. Ellen Kandeler
Project manager
Prof. Dr. Ellen Kandeler
Universität Hohenheim
Dr. Sven Marhan
Project manager
Dr. Sven Marhan
Universität Hohenheim
Aurelia Gebala
Employee
Aurelia Gebala
Universität Hohenheim
Dr. Runa Boeddinghaus
Employee
Dr. Runa Boeddinghaus
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